treatment of domestic wastewater using two substrates of constructed wetland planted with phragmites australis in arid regions (southeast algeria, biskra)

Constructed wetlands (cws) have been widely recognised for efficiently removing many pollutants from wastewater, making them vital for environmental bioremediation. the substrates used in constructed wetlands are crucial in determining their overall performance, notably their ability to improve nitrogen and phosphorus removal from wastewater. this study aims to investigate the possibility of removing pollutants from wastewater using a pilot scale vertical flow constructed wetland (vfcw) planted with phragmites australis applied to various substrates, such as gravel and sand in an arid climate in southeast algeria.the study involved using four basins, filled with sand and gravel. two were planted with phragmites australis and the others were left as a control without vegetation. the efficiency of the filtration systems was evaluated based on various physicochemical and organic parameters. results showed that the highest hydraulic retention time is in the 7 days. the removal efficiency values are 84.38% for biological oxygen demand (dbo5), 77.45% for chemical oxygen demand (cod), and 83.30% for total solid matter (tss) in the planted gravel filter. the planted sand filter had even higher removal efficiency values, with 89.59%, 85.80%, and 86.63% for dbo5, cod, and tss, respectively. nitrate concentration increased in all filters due to the complete transformation of ammonium into nitrate. no2-, nh4+, and po43- removal efficiencies were also higher in the planted sand filter 74.45%, 95.43%, and 77.64%, respectively.